1. Field of the Invention
The present invention relates to an electrophotographic photosensitive member, a process cartridge and an electrophotographic apparatus each having an electrophotographic photosensitive member, and to a phthalocyanine crystal.
2. Description of the Related Art
Since a semiconductor laser commonly used in an image exposing device of an electrophotographic photosensitive member has a long oscillation wavelength in the range of 650 to 820 nm, electrophotographic photosensitive members having high sensitivity to light in the long wavelength range are currently under development. Electrophotographic photosensitive members having high sensitivity to the light of a semiconductor laser with a short oscillation wavelength is also recently under development so as to achieve high resolution images.
Azo pigments and phthalocyanine pigments are known as charge generating substances having high sensitivity to the light ranging from the long wavelength region to the short wavelength region.
Although an electrophotographic photosensitive member using an azo pigment or a phthalocyanine pigment has excellent sensitivity properties, a problem is that the generated photo carriers tend to remain in the photosensitive layer so as to act as a memory, easily causing potential variation such as ghosting in some cases.
In order to solve the problem of a phthalocyanine pigment, the phthalocyanine pigment has been used in combination with a specific azo pigment.
An acetophenone compound for use in an electrophotographic photosensitive member is described in Japanese Patent Application Laid-Open No. S59-30541, Japanese Patent Application Laid-Open No. 2007-138153 and Japanese Patent Application Laid-Open No. 2009-301016.
An acetylated benzene derivative for use as absorption wavelength shifting agent for a phthalocyanine vapor deposited film is described in Japanese Patent Application Laid-Open No. S59-30541.
Titanylphthalocyanine crystal having a main peak at a Bragg angle 2θ of 27.2° in X-ray diffraction using CuKα radiation, produced by contacting a phthalocyanine crystal precursor with a fluorobenzene derivative, is described in Japanese Patent Application Laid-Open No. 2007-138153. According to its description, the titanylphthalocyanine crystal thus produced has both improved stability of the crystal and improved sensitivity.
According to Japanese Patent Application Laid-Open No. 2009-301016, an α-aminoacetophenone compound as a polymerization initiator is added to the protective layer of a photosensitive member so as to improve the hardenability.
Various attempts have been made to improve electrophotographic photosensitive members as described above. For further improvement in high-quality images in recent years, it is desired to prevent image degradation due to ghosting in various environments.